Simplified buildout configuration by removing references to '${buildout:eggs}'.

They are not needed because there is only one egg (Zope2) required for each part.

buildout.cfg

@@ -9,12 +9,10 @@ parts =
 extends = versions-zope2.cfg
 versions = versions
 unzip = true
-eggs =
-    Zope2
 
 [test]
 recipe = zc.recipe.testrunner
-eggs = ${buildout:eggs}
+eggs = Zope2
 
 [scripts]
 recipe = zc.recipe.egg:scripts
@@ -22,6 +20,6 @@ eggs = Zope2
 
 [zopepy]
 recipe = zc.recipe.egg
-eggs = ${buildout:eggs}
+eggs = Zope2
 interpreter = zopepy
 scripts = zopepy